Accelerated development of battery technologies heightens an interest in co-locating battery energy storage systems (BESSs) with renewable power plants for stacking of multiple revenue streams such as frequency response services to AC grids. Frequency response market reforms in the UK introduce new end-state services and require evaluating techno-economic feasibility of co-location projects in new circumstances. This paper develops a BESS optimisation method to optimize capacity and operating strategy of a co-located BESS for providing latest Dynamic Containment (DC) services based on the UK perspective. BESS optimisation method simulates BESS delivering DC responses and following operational baselines for state of energy (SoE) restoration

as well as

coordinating with its co-located power plant. Then net present value of BESS co-location project is estimated from power flows across the system and maximised to suggest optimal BESS capacity

target energy footroom and/or headroom levels for baseline estimation

and possible SoE ranges suitable for energy interchange with its co-located power plant. BESS optimisation method is tested based on a particular transmission-level wind farm in the UK and discussed alongside operation and profitability of a BESS co-location project under frequency response market reforms.